(1) Field of the Invention
The present invention relates to a blood pressure measurement device and methods for measuring blood pressure. More specifically, the present invention relates to apparatus and methods for determining whether a patient was in a rest condition during blood pressure measurement.
(2) Description of Related Art
A rest condition of a patient is important when measuring blood pressure. If the patient is not in a rest condition, the measured blood pressure may differ from the value measured in the rest condition. Thus, it is necessary to know whether the patient was in the rest condition when the blood pressure was being measured.
As a measure to determine whether a patient was in a rest condition, measuring pulse rate and pulse wave period is known. Generally, the patient's pulse wave period becomes short or unstable after hard exercise or mental distress. Therefore, it is possible to determine whether the patient was in the rest condition by examining whether the patient's pulse wave period was stable during a certain period of time.
Rossmax Hemodynamic Stability Determination (HSD) discloses that when a patient is not in a rest condition due to mental or physical load, his or her pulse period may become short and/or unstable, which may cause blood pressure measurement error.
JPH2012-120206 discloses the relationship between an increase of pulse rate and pulse period change at the time when a patient received stress.
However, because most blood pressure devices require use of a cuff to be mounted on an arm of the patient, some patients may feel stress during blood pressure measurement. In that event, the pulse period of the patient may be significantly affected by the stress that was caused by the cuff. Therefore, even if the patient was a under rest condition before measurement, the pulse period measured by using the blood pressure measurement device may become different from the pulse period of the patient in the rest condition.